Method and apparatus for obtaining pure spray water for steam desuperheating purposes

ABSTRACT

This invention relates to a method and apparatus for obtaining pure spray water for steam desuperheating purposes wherein a portion of the steam produced in the boiler is passed through a condensing chamber, and the liquid condensate is then used as the spray water.

United States Patent [72] Inventor Albert II. Rawdon, .Ir.

Shrewsbury. Mas.

121 Appl. No 832,265

221 Filed June 11. I969 [45) Patented July 6, i971 [73] Assignee RileyStoker Corporation Worcester, Mass.

[54] METHOD AND APPARATUS FOR OBTAINING PURE SPRAY WATER FOR STEAMDESUPERHEATING PURPOSES 10 Claims, 1 Drawing Fig.

[52] U.S. Cl 165/1, 165/40, l65/66, 122/487, 261/160 [51] lnt.Cl B60h1/00 501 FieldoiSearch 165/66, 111.40, 60, 144, 107; 122/487; 26l/l60;60/104 [5 6] References Cited UNITED STATES PATENTS 2,550,683 5/l95lFletcher et al Primary Examiner-Charles Sukalo Att0rneyWard, McElhannon,Brooks & Fitzpatrick ABSTRACT: This invention relates to a method andapparatus for obtaining pure spray water for steam desuperheatingpurposes wherein a portion of the steam produced in the boiler is passedthrough a condensing chamber, and the liquid condensate is then used asthe spray water.

METHOD AND APPARATUS FOR OBTAINING PURE SPRAY WATER FOR STEAMDESUPERHEATING PURPOSES This invention relates to a method and apparatusfor obtaining pure spray water for desuperheating purposes when theboiler feed water is contaminated. lt will be appreciated that in bothutility and shipboard installations the boilers operate with acondenser, and hence recirculate substantially all of the feed water. Onthe other hand, in many industrial applications there is substantially100 percent makeup feed water. This disclosure relates to the latterapplication and, accordingly, the feed water is of a relatively lowpurity and cannot satisfactorily be used in a spray-type desuperheater.Applicant has discovered a novel combination of elements combined insuch a way as to afford a very economical, efficient and practicalsolution of the difficulties in the problem above discussed, as willbecome apparent as the description proceeds.

Briefly, in a power generating system wherein steam from a boiler ispassed through a superheater and a spray-type desuperheater, myinvention contemplates the provision of a new and improved method ofprocessing spray water for said desuperheater characterized by the stepsof withdrawing steam from the boiler and passing it to a heat exchangechamber, condensing the steam in this heat exchange chamber by passingcool boiler feed water through a coil mounted therein. The next step isto withdraw the condensed steam and pass it to the desuperheater, asspray water.

In a power-generating system having a boiler, a superheater and a spraytype desuperheater, my invention, in another form thereof, contemplatesthe provision of a combination of ele ments including a heat exchangechamber, means for withdrawing steam from the boiler and passing it tothe heat exchange chamber, means for passing boiler feed water throughthe chamber to condense the steam, and means for withdrawing the socondensed steam from the chamber and passing it to the desuperheater.

There has thus been outlined rather broadly the more importantfeaturesof the invention in order that the detailed description thereof thatfollows may be better understood, and in order that the presentcontribution to the art may be better appreciated. There are, of course,additional features of the invention that will be described hereinafterwhich will form the subject of the claims appended hereto. Those skilledin the art will appreciate that the conception on which this disclosureis based may readily be utilized as the basis for the designing of otherstructures for carrying out the several purposes of the invention. It isimportant, therefore, that this disclosure be regarded as including suchequivalent constructions as do not depart from the spirit and scope ofthe invention.

One embodiment of the invention has been chosen for purposes ofillustration and description, and is shown in the accompanying drawingforming a part of the specification, wherein:

The FIGURE is a schematic diagram of a power-generating system embodyingthe concept of my invention for obtaining pure spray water for steamdesuperheating purposes.

In the embodiment of the invention illustrated, the apparatus forobtaining pure spray water for desuperheating purposes comprises aninlet pipe with a throttle valve 12 through which approximately 300,000lbs. per hour of feed water enters the system at a temperature of about220 F. for

example. The boiler feed water passes to a member 14 which may be aneconomizer, a fixed orifice plate or a throttle valve with a pressuredrop of the order of about 15 psi, and from there along line 16 to aboiler 18. When the member 14 is an economizer it raises the boiler feedwater to a temperature of about 402 F. The steam leaves the boiler at atemperature of about 540 F. and a pressure of about 1,000 p.s.i.g.passes along line 20 to the first stage 22 of a superheater, and then toa desuperheater indicated generally at 24. It will be appreciated thatany suitable type of spray desuperheater may be employed as will bediscussed more fully hereinafter. From the desuperheater, the steampasses to the second stage superheater, the steam passes to the secondstage superheater 26 and then to the turbine through a main steam line28 at a temperature of about 850 F. and a pressure of about 900 p.s.i.g.

In order to provide pure spray water for the desuperheater 24, a heatexchange or condensing chamber 30 is provided which receives steam fromthe boiler 18 through line 32. The steam is condensed in chamber 30 andthe condensate so formed passes along line 34 to the desuperheater 24.In order to condense the steam in the chamber 30, cold boiler feed wateris taken from line 10, passed along line 36 and through a coil 38 in thechamber 30. The so heated feed water is then led back into the feed line16 as by means ofline 40, provided for the purpose.

lt will be appreciated that temperature control of the steam leaving thesuperheater for the turbine is effected by the introduction of spraywater through a spray nozzle 42 in the desuperheater 24. The steamtemperature is sensed in the main steam line 28 by a thermocouple 44, orother such device, in response to which temperature spray throttle valve46 is actuated to control the flow through the spray nozzle 42 andthereby control the amount of desuperheating desired. A level control,indicated at 48, used in combination with a throttle valve 50 serves tocontrol the volume of cooling water entering the coil 38 in chamber 30,thereby controlling the volume of steam condensed in the chamber. Whenthe member 14 is a throttle valve, it may be linked, as by means oflinkage 51, to the throttle valve 50 so that as valve 51 opens, valve 50closes and when valve 50 opens, valve 51 closes. A hand-operatedisolation valve 52 is provided.

It will thus be seen that the present invention does indeed provide animproved method and apparatus for obtaining pure spray water for steamdesuperheating purposes which is superior in simplicity, economy andefficiency as compared to prior-art such devices.

Although a particular embodiment of the invention is herein disclosedfor purposes of explanation, various modifications thereof, after studyof this specification, will be apparent to those skilled in the art towhich the invention pertains.

What I claim and desire to be secured by letters patent is:

1. In a power-generating system having a boiler, a superheater, pipingmeans for carrying steam from the boiler to the superheater, and aspray-type desuperheater piping means for carrying superheated steamfrom said superheater to said desuperheater, the combination comprisinga heat exchange chamber, means for withdrawing steam from said boilerand passing it to said heat exchange chamber, means for passing boilerfeed water through said chamber to condense said steam, and means forwithdrawing the condensate from said chamber and passing it to saiddesuperheater as spray water.

2. Apparatus according to claim 1 wherein said means for passing boilerfeed water through said chamber to condense said steam comprises a firstpipeline leading from the boiler feed line to said chamber, a secondpipeline leading from said chamber to said boiler feed line, a fixeddiameter orifice mounted in said boiler feed line between said first andsecond pipelines to cause a pressure drop.

3. Apparatus according to claim 1 wherein said means for passing boilerfeed water through said chamber to condense said steam comprises a firstpipeline leading from the boiler feed line to said chamber, a throttlevalve mounted in said first pipeline, a condensate level controlindicator mounted on said chamber for controlling said throttle valve, asecond pipeline leading from said chamber to said boiler feed line, asecond throttle valve mounted in said boiler feed line between saidfirst and second pipeline, means for operating said second throttlevalve responsive to operation of said first throttle valve.

4. Apparatus according to claim 1 wherein means for passing boiler feedwater through said chamber to condense said steam comprises a coilmounted within said chamber which receives boiler feed water from theboiler feed water inlet pipe before the economizer and discharges boilerfeed water to the boiler feed water line after the economizer.

5. Apparatus according to claim 1 wherein said means for passing boilerfeed water through said chamber to condense said steam comprises apipeline leading from the boiler feed line to said chamber andcontaining a throttle valve, and a condensate level control indicatormounted on said chamber for controlling said throttle valve.

6. Apparatus according to claim 1 wherein said means for withdrawing thecondensed steam from said chamber and passing it to said desuperheateras spray water comprises a pipeline containing a spray throttle valve,and a thermocouple mounted in the main steam line for controlling saidthrottle valve.

7. in a power-generating system having an economizer, a boiler, a boilerfeed water inlet line having a first portion for feeding boiler feedwater into said economizer and a second portion for receiving feed waterfrom said economizer and carrying it to said boiler, a superheater,piping means for carrying steam from the boiler to the superheater, anda spraytype desuperheater, piping means for carrying superheated steamfrom said superheater to said desuperheater, the combination comprisinga heat exchange chamber, a pipeline containing a manually operatedthrottle valve for withdrawing steam from said boiler and passing it tosaid heat exchange chamber, a coil mounted within said chamber, apipeline lead ing from said first portion of the boiler feed water inletline to one end of said coil, a pipeline leading from the other end ofsaid coil to the second portion of the boiler feed water inlet line, athrottle valve mounted in said line leading from said first portion ofthe boiler feed water inlet line to said coil, a condensate levelcontrol indicator mounted on said chamber for controlling said throttlevalve, a pipeline extending from said chamber to said desuperheater forwithdrawing condensed steam from said chamber and passing it to saiddesuperheater, a spray throttle valve mounted in said last namedpipeline, a thermocouple mounted in the main steam line for controllingsaid spray throttle valve.

8. In a power-generating system wherein steam from a boiler is passedthrough a superheater and a spray-type desuperheater, the method ofprocessing spray water for said desuperheater comprising the steps ofwithdrawing steam from said boiler and passing it through a heatexchange chamber, condensing said steam in said heat exchange chamber bypassing cool boiler feed water through a coil in said heat exchangechamber, withdrawing the condensate from said chamber and passing itthrough said desuperheater as spray water.

9. In a power-generating system wherein steam from a boiler is passedthrough a superheater and a spray-type desuperheater, the method ofprocessing spray water for said desuperheater comprising the steps ofwithdrawing steam from said boiler and passing it through a heatexchange chamber, condensing said steam in said heatexchanger chamber bypassing cool boiler feed water through a coil in said heat exchangechamber, controlling the flow of boiler feed water into said chamber tocontrol the volume of steam condensed in said chamber, withdrawing thecondensate from said chamber and passing it through a spray nozzle insaid desuperheater, and controlling the flow of condensate to saiddesuperheater to obtain the desired desuperheating.

10. A power-generating system according to claim 7 further comprising asecond stage superheater and piping means for receiving the steam fromsaid desuperheater and carrying it to said second stage superheater, andsaid thermocouple being mounted in the main steam line at a locationafter said second stage superheater.

2. Apparatus according to claim 1 wherein said means for passing boilerfeed water through said chamber to condense said steam comprises a firstpipeline leading froM the boiler feed line to said chamber, a secondpipeline leading from said chamber to said boiler feed line, a fixeddiameter orifice mounted in said boiler feed line between said first andsecond pipelines to cause a pressure drop.
 3. Apparatus according toclaim 1 wherein said means for passing boiler feed water through saidchamber to condense said steam comprises a first pipeline leading fromthe boiler feed line to said chamber, a throttle valve mounted in saidfirst pipeline, a condensate level control indicator mounted on saidchamber for controlling said throttle valve, a second pipeline leadingfrom said chamber to said boiler feed line, a second throttle valvemounted in said boiler feed line between said first and second pipeline,means for operating said second throttle valve responsive to operationof said first throttle valve.
 4. Apparatus according to claim 1 whereinmeans for passing boiler feed water through said chamber to condensesaid steam comprises a coil mounted within said chamber which receivesboiler feed water from the boiler feed water inlet pipe before theeconomizer and discharges boiler feed water to the boiler feed waterline after the economizer.
 5. Apparatus according to claim 1 whereinsaid means for passing boiler feed water through said chamber tocondense said steam comprises a pipeline leading from the boiler feedline to said chamber and containing a throttle valve, and a condensatelevel control indicator mounted on said chamber for controlling saidthrottle valve.
 6. Apparatus according to claim 1 wherein said means forwithdrawing the condensed steam from said chamber and passing it to saiddesuperheater as spray water comprises a pipeline containing a spraythrottle valve, and a thermocouple mounted in the main steam line forcontrolling said throttle valve.
 7. In a power-generating system havingan economizer, a boiler, a boiler feed water inlet line having a firstportion for feeding boiler feed water into said economizer and a secondportion for receiving feed water from said economizer and carrying it tosaid boiler, a superheater, piping means for carrying steam from theboiler to the superheater, and a spray-type desuperheater, piping meansfor carrying superheated steam from said superheater to saiddesuperheater, the combination comprising a heat exchange chamber, apipeline containing a manually operated throttle valve for withdrawingsteam from said boiler and passing it to said heat exchange chamber, acoil mounted within said chamber, a pipeline leading from said firstportion of the boiler feed water inlet line to one end of said coil, apipeline leading from the other end of said coil to the second portionof the boiler feed water inlet line, a throttle valve mounted in saidline leading from said first portion of the boiler feed water inlet lineto said coil, a condensate level control indicator mounted on saidchamber for controlling said throttle valve, a pipeline extending fromsaid chamber to said desuperheater for withdrawing condensed steam fromsaid chamber and passing it to said desuperheater, a spray throttlevalve mounted in said last named pipeline, a thermocouple mounted in themain steam line for controlling said spray throttle valve.
 8. In apower-generating system wherein steam from a boiler is passed through asuperheater and a spray-type desuperheater, the method of processingspray water for said desuperheater comprising the steps of withdrawingsteam from said boiler and passing it through a heat exchange chamber,condensing said steam in said heat exchange chamber by passing coolboiler feed water through a coil in said heat exchange chamber,withdrawing the condensate from said chamber and passing it through saiddesuperheater as spray water.
 9. In a power-generating system whereinsteam from a boiler is passed through a superheater and a spray-typedesuperheater, the method of processing spray water for saiddesuperheater comprising the steps of withdrawing steam from said boilerand passing it through a heat exchange chamber, condensing said steam insaid heat exchanger chamber by passing cool boiler feed water through acoil in said heat exchange chamber, controlling the flow of boiler feedwater into said chamber to control the volume of steam condensed in saidchamber, withdrawing the condensate from said chamber and passing itthrough a spray nozzle in said desuperheater, and controlling the flowof condensate to said desuperheater to obtain the desireddesuperheating.
 10. A power-generating system according to claim 7further comprising a second stage superheater and piping means forreceiving the steam from said desuperheater and carrying it to saidsecond stage superheater, and said thermocouple being mounted in themain steam line at a location after said second stage superheater.